How to crack Google coding Interview?

There are many scary stories floating around about Google interviews, but it’s mostly just that: stories. The interview is not terribly different from Microsoft’s or Amazon’s. However, because Google HR can be a little disorganized, we recommend being proactive in communication.
A Google engineer performs the first phone screen, so expect tough technical questions. On your on-site interview, you'll interview with four to six people, one of whom will be a lunch interviewer. Interviewer feedback is kept confidential from the other interviewers, so you can be assured that you enter each interview with blank slate. Your lunch interviewer doesn’t submit feedback, so this is a great opportunity to ask honest questions.

Written feedback is submitted to a hiring committee of engineers to make a hire/no-hire recommendation. Feedback is typically broken down into four categories (Analytical Ability, Coding, Experience and Communication) and you are given a score from 1.0 to 4.0 overall.
The hiring committee understands that you can’t be expected to excel in every interview, but if multiple people raise the same red flag (arrogance, poor coding skills, etc), that can disqualify you. A hiring committee typically wants to see one interviewer who is an “enthusiastic endorser.” In other words, a packet with scores of 3.6, 3.1, 3.1 and 2.6 is better than all 3.1s. Your phone screen is usually not a strong factor in the final decision.

The Google hiring process can be slow. If you don’t hear back within one week, politely ask your recruiter for an update. A lack of response says nothing about your performance.


Definitely Prepare:
As a web-based company, Google cares about how to design a scalable system. So, make sure you prepare for questions from “System Design and Memory Limits” Additionally, many Google interviewers will ask questions involving Bit Manipulation, so please brush up on these questions.


What’s Different:
Your interviewers do not make the hiring decision. Rather, they enter feedback which is passed to a hiring committee. The hiring committee recommends a decision which can be—though rarely is—rejected by Google executives